Subject: [PATCH v2 07/15] drm/mxsfb: Fix the vblank events

From: Robert Chiras <[email-masked]>
Date: Wed, 14 Aug 2019 13:48:43 +0300

Currently, the vblank support is not correctly implemented in MXSFB_DRM
driver. The call to drm_vblank_init is made with mode_config.num_crtc
which at that time is 0. Because of this, vblank is not activated, so
there won't be any vblank event submitted.
For example, when running modetest with the '-v' parameter will result
in an astronomical refresh rate (10000+ Hz), because of that.

Signed-off-by: Robert Chiras <[email-masked]>
---
 drivers/gpu/drm/mxsfb/mxsfb_drv.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
index 2743975..829abec 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
@@ -38,6 +38,9 @@
 #include "mxsfb_drv.h"
 #include "mxsfb_regs.h"
 
+/* The eLCDIF max possible CRTCs */
+#define MAX_CRTCS 1
+
 enum mxsfb_devtype {
 	MXSFB_V3,
 	MXSFB_V4,
@@ -138,6 +141,8 @@ static void mxsfb_pipe_enable(struct drm_simple_display_pipe *pipe,
 		mxsfb->connector = &mxsfb->panel_connector;
 	}
 
+	drm_crtc_vblank_on(&pipe->crtc);
+
 	pm_runtime_get_sync(drm->dev);
 	drm_panel_prepare(mxsfb->panel);
 	mxsfb_crtc_enable(mxsfb);
@@ -164,6 +169,8 @@ static void mxsfb_pipe_disable(struct drm_simple_display_pipe *pipe)
 	}
 	spin_unlock_irq(&drm->event_lock);
 
+	drm_crtc_vblank_off(&pipe->crtc);
+
 	if (mxsfb->connector != &mxsfb->panel_connector)
 		mxsfb->connector = NULL;
 }
@@ -246,7 +253,7 @@ static int mxsfb_load(struct drm_device *drm, unsigned long flags)
 
 	pm_runtime_enable(drm->dev);
 
-	ret = drm_vblank_init(drm, drm->mode_config.num_crtc);
+	ret = drm_vblank_init(drm, MAX_CRTCS);
 	if (ret < 0) {
 		dev_err(drm->dev, "Failed to initialise vblank\n");
 		goto err_vblank;
@@ -269,6 +276,8 @@ static int mxsfb_load(struct drm_device *drm, unsigned long flags)
 		goto err_vblank;
 	}
 
+	drm_crtc_vblank_off(&mxsfb->pipe.crtc);
+
 	/*
 	 * Attach panel only if there is one.
 	 * If there is no panel attach, it must be a bridge. In this case, we
-- 
2.7.4

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